Telephone system



Dec. 3, 1929. L. H. JOHNSON 1,738,298

TELEPHONE SYSTEM Filed Jan. 17, 1928 UPRIS 721.

MAM/M41.

/N|/ENTOR LEW/s /7 JOHNSON 5) W ATTURNE Y Patented Dec. 3, 1929 UNITEFries LEWIS H. JOHNSON, F MADISON, NEW JERSEY, ASSIGNOR T0 BELLTELEPHONE LAB- OBATGRIES, INCORPQRATED, OF NEW YORK, N. Y., ACORPORATION OF NEW YORK TELEPHONE SYSTEM lipplfmationv filed January 17,1928. Serial No. 247,275.

This invention relates to telephone systems and particularly to systemsin which substation meters are operated under control of mechanism atthe central office.

Its objects are to safeguard the subscriber against overcharges and tosimplify and improve the equipment used at the central office forcontrolling the substation meters.

In the past systems have been proposed for operating a substationregister by periodically reversing the current in the subscribers lineduring conversation. In these systems, the endeavor to reduce as much aspossible the disturbance in the subscribers line due to current changeshas led to the use of com plicated and expensive devices for making thereversals.

According to the present invention an advantage is secured over theseprior systems by the provision of a simple and efficient currentreversing mechanism comprising a current supply circuit, common to anumber of connecting circuits, having a current reversing device andmeans for preventing sudden changes in the current including choke coilsin series with the supply circuit and a shunt condenser. The commoncircuit is normally disconnected from the connecting circuits and isassociated with any desired one of said circuits by an individualconnecting relay controlled by the called supervisory relay.

A feature of the invention is an arrangement in which a delay isintroduced between the time when the supervisory relay operates and thetime when the register operating device commences to function. Thisdelay prevents false charging due to momentary interruptions of thecircuit.

Another feature is, a system in which the calling party may recall theoperator before the called party has released without causing the meteroperating mechanism to function.

A further feature is a ringing circuit in which the direct currentassociated with the ringing source is prevented from flowing over thesubscribers line and causing the false operation of his meter.

Still another feature is an arrangement to prevent the connection of thecurrent supply circuit to the calling line when the battery isinreversed condition. This avoids 0bjectionable noise in the subscribersreceiver.

The drawing illustrates a portion of a telephone system in whichsubscribers lines appear at an operators position. Two of these lines, Aand B, are shown terminating in jacks 3 and 5 respectively at theoperators position. The lines A and B are equipped respectively withsubstation meters 1 and 2. These meters are designed to operate atsuccessive intervals during conversation in response to repeatedreversals of current in the line. i

The operators position is equipped with a number of cord circuits suchas the cord '0 partly shown in detail in the drawin A current supply andreversing circuit 23 is provided in common to a number of cord circuitsC. This supply circuit consists of battery 24, a battery reversing relay25, choke coils 27 and 28 and condenser 31. The cord circuit C isprovided with two relays 32 and 33 for connecting the common supplycircuit 23 to the tip and ring conductors of the cord through thewinding of the repeating coil 7. 'Similar relays are provided for eachof the cord circuits. i

It is believed that an understanding of the invention will best be hadfrom a detailed description of the operation of the system. Assume thatthe subscriber of line A wishes to hold conversation with the subscriberof line B. The calling subscriber initiates the call in the usual mannerand the operator respondsby inserting the plug 4 of an idle.

cord circuit C in the jack 3. When the plug is inserted in the jack acircuit is completed from battery, through the lamp ll, resistance 14,lower back contact of relay 34c, sleeve of the plug 4 and jack 8 toground. At the same time another circuit is completed from, the negativepole of battery 24, through the choke coil 29, normal contacts of relay33, lower left winding of repeating coil 7, winding of relay 8, andthence over the ring side of the subscribers line and returning over thetip side through the upper left winding of repeating coil 7, normalcontacts of relay 33,

choke coil 26 to the grounded pole of battery 24. Relay 8 operates inthis circuit and completes a circuit from the interrupter 15, throughthe upper inner back contact of relay 16, contact of'relay 8,resistances 12 and 14, back contact of relay 34 to ground at the Vsleeve of the jack 3. Each time the inter- Relay 16'operates in thiscircuit and comletes a holding circuit from ground, through its upperwinding and contact, contact of the supervisory relay 8 to batterythrough the upper contact of relay 16. The relay 16 in operatingdisconnects the interrupter 15 to discontinue the flashing of the lamp11. The lampisnow continuously shunted by the circuit through the upperwinding and contact of relay 16 and contact of the supervisory relay 8.Relay 16 also closes a circuit from battery, through its lower windingand contact, winding of relay to ground at the upper contact of relay34. While the operators talking key 10 remains depressed, however,

rela .35 is shuntedand does not operate.

The operator, having obtained the number of the called line, releasesthe talking key 10, seizes the plug 6 and inserts'it in the jack 5 ofthe called line B. The release of the key 10 removes the shunt andpermits relay 35 to operate in series with the lower windin of relay 16.I The insertion of the plug 6 in ack 5 results in the closure of acircuit from battery, through the. lamp 45, resistance 46 to oundthrough thesleeve of plug .6 and jack 5. Lamp 45 lights in thiscircuit."

The operator'now proceeds to apply ringingcurrent to the: called line tosignal the I wanted subscriber. For this purpose her cord circuit isequipped with ringing keys 36, 37, 38 and 39 which serveto apply ringingcurrent from the sources 47 and 48 either to one side of the. line orthe other according to the character of the called line. 47 and 48 maysupply any well-known type of ringing current, such as alternatingcurrent superimposed on direct current. Assume that the key .37 is theone used for signaling the wanted subscriber on line B. The opera tormanipulates this key and a circuit is closed fromthe ringing source 47,through the'marginal relay 42",'contact of said relay, left contactofrelay 44, upper alternate contact of key'BZ, through the normalcontacts of keys .38 and 39, tip of the plug 6 and the jack 5,

theme over the subscribers line to the bell at thesubstation andreturning over the ring The sourcesside of the line through the normalcontacts of keys 39 and 38, alternate contact of key 37 to ground. Therelay 42 being marginal does not operate until the called subscriberanswers. The ringing current causes the operation of the subscribersbell and, when he answers, the resistance of the loop is suflicientlydecreased to permit the operation of relay 42. Relay 42 at its contactopens the direct current path so that direct current from the source 47cannot continue to flow over the subscribers loop in case the operatorholds the ringing key depressed after the called subscriber hasanswered. The alternating ringing current, however, continues to flowthrough the winding of relay 42, condenser 49, winding of relay andthence over the circuit previously traced if the key is held depressed.Relay 40 operates due to this current and closes an obvious circuit forrelay 44. Relay 44 opens the original direct current circuit so that inthe event of relay 42 releasing, this circuit is not completed to permitthe flow of direct current over the called subscribers loop. Thisarrangement eliminates the danger of falsely operating the subscribersmeter 2 which is designed to respond to direct current only.

When the called subscriber answers, a circuit is completed from the freepole of battery 24, choke coil 29, lower right winding of repeating coil7, supervisory relay 9, through the normal contacts of the ringing keys,thence over the loop of the subscribers line and returning through theringing keys, upper right winding of coil 7, choke coil 26 to thegrounded pole of battery 24. Relay 9 operates in this circuit and closesa circuit from battery, through its contacts, upper front contact ofrelay 35, winding of relay 32 to ground. Relay 32 closes a circuit frombattery, through its inner lower contact, front contacts of relay 35,resistance 50, resistance 46 to ground at the sleeve of jack 5. Thiscircuit shunts the lamp which becomes extinguished.

The operation of relay 32 renders the interrupter 17 effective to bringabout the connection of the battery supply circuit 23 to the callingsubscribers line. The interrupter 17 through its segment 18 causes therepeated operation and release of the battery reversing relay 25.Accordingly, the battery 24 may be in reversed or its non-reversedcondition when the called subscriber answersand relay 32 operates. Ifthe battery is in its non-reversed condition it is proper to connect thesupply circuit 23 to the calling line immediately. If, however, thebattery is reversed the supply circuit should not be connected to thecalling line. To do so would bring about an abrupt reversal of currentfrom the line producing a disagreeable noise in the calling subscriberscircuit. Assume first that the battery 24 is III in its normal conditionin which case the relay 25 is deenergized as shown. Relay 32 inoperating, therefore, closes a circuit from ground through its innerupper contact,

winding of relay 33, lower normal contacts of relay 33, resistance 22,through the segments 20 and 19 to battery. Relay 33 operates at once andin so doing connects the supply circuit 23 throughthe left winding ofrepeating coil 7 to the calling subscribers line. A circuit may now betraced from free pole of battery 24, lower back contact of relay 25,choke coil 28, lower contact of re..ay 32, inner lower contact of relay33, lower leftwinding' of coil 7, and thence over the subscribefls lineand returning through the upper left winding of coil 7, upper con tactof relay 33, upper contact of relay 32, choke coil 27, upper backcontact of relay 25 to the grounded pole of battery 2%. It will be seenthat the direction of current flow over the subscribers line in thiscase is the same it was before the supply circuit 23 was connectedthereto.

llelay 33 in operating locks in a circuit from battery, through itslower front contacts, winding of said relay to ground at the contact ofrelay 32. As the interrupter l? continues its rotation the relay 25 isalternately operated and released at periodic intervals. During eachoperation and release of relay 25, the currentin the calling line isreversed to cause the operation of the substation meter 1.

assume next that the battery 24 is in its reversed condition at the timethe called subscriber answers. Relay 32 in operating now completes acircuit from ground through the winding of relay 33, lowernormalcontacts of relay 33, resistance 22, through the segments 20 and 21 toground. Therefore, the relay 33 noes not operate and the connection ofthe supply circuit 28 to the calling line lelayed. l fhen, later, thesegment 20 ts, the circuit above traced is completed from battery,through the relay 83 to ground and relay 38 operates to connect thesupply circuit to the calling line.

After the operator answers the calling subscriber, if she finds thecalled line busy, it is rommon practice to insert the plug 6 in the jackof a busy-back circuit. The busy-back apparatus operates in thewell-known man ner to cause the repeated and rapid opening and closingof the cord circuit. This causes the repeated operation of relay 9 andrelay Should the relay 32 be permitted to re 0.0- lease just before thebattery 24; is reversed and to actuate just after reversal, the callingsubscriber will be as essed with a false charge. To prevent this aninterval of about two seconds is introduced before the battery 2% isreversed. During this interval if the relay is released due to thebusy-back apparatus or due to the called subscriber flashing hisswitchhook, it will not reoperate to cause a false charge when thebattery 2& is reversed subsequently. This is due to the manner in whichthe segment 20 is cut as will be clear from an inspection of thedrawing. Thus, it will be seen that the calling subscriber is guardedagainst false operation of his meter. If a short interruption occurs inthe cord circuit or in the called line within the two second intervalprior to the reversal of current, the supply circuit 23 is disconnect edfrom the calling line, but is not reconnected thereto until a completecharge interval has expired.

At the end of conversation the subscribers replace their receivers onthe switchhooks.

When the called subscriber hangs up his re-.

ceiver, relay 9 releases, causing the release of relay 32 which in turnreleases the relay 3?, disconnecting the reversing circuit from thecalling line. If the calling subscriber lirst hangs up his receiver hisline is opened at the switchhook contacts to render the meter operatingcircuit inel'l'ective. The calling subscriber by hanging up his receiveralso causes the release of relay 8, which opens the holding circuitthrougl'i the upper winding of relay 16. The energization of the lowerwinding of relay 16 is not sufficient to hold the relay operated.Accordingly, this relay releases, in turn releasing the relay The lamp11 illuminates to advise the operator that the calling subscriber hasreplaced his receiver. The lamp 45 also lights in an obvio-us circuitand the operator takes down the connection by removing the plugs fromthe jacks.

It may happen that the calling subscriber wishes to recall the operatorafter complet ing his conversation with the called party. Since heshould be entitled to make a recall without charge, provision is made toprevent the operation of his meter in case the called subscriber has notreplaced his receiver on the switchhoolr. So long as the calledsubscriber keeps his receiver oil the switchhoolc and until the operatorwithdraws the plug, the relay 9 remains operated and if relay 35 ispermitted to recperate the charging mechanism will be connected to thecalling subscribers line.

The calling subscriber on replacing his receiver temporaril and thenremoving it to initiate the reca l releases the relay 8 as explained,resulting in the release of relay 16. The subsequent removal of thereceiver permits relay 8 to reoperate and the lamp l1 is flashed aspreviously described. The operator, seeing the lamp 11 flashing, lrnowsthat the calling subscriber is recalling and be fore taking down theconnection she answers him again to ascertain what he desires. Indepressing the key 10 the circuit previously traced is closed throughthe lower winding of relay 16 and the back contact of relay 35. Relay 16reoperates and discontinues ator is conversing with the callingsubscriber the key 10 is depressed and relay 35 is shunted ;so that itdoes'not operate in series with relay 16.5 So long as relay 35 remainsdeenergized the circuit for relay 32 isheld open and the chargingmechanism cannot be connected to the calling line. Therefore, thecalling subscriber may recall the operator without causing the operationof his meter 1.

g If the called subscriber wishes to converse again With the calledparty, the operator disconnects her headset and in so doing rendersthe'charging mechanism eftective. If the called subscriber has releasedin the meantime, she recalls him by applying ringing current to the linein the manner described. If, on the other hand, the calling subscriberwishes to converse with another subscriber the proper connection isestablished.

Although the invention has been illustrated as applied toa system of themanual type it will be understood that it is also applicable toautomatic systems. It will be further understood that numerous changesand alterations may be made in the circuits and apparatus illustratedwithout departing from the spirit of the invention.

The substation meter illustrated diagrammatically may be of any suitabletype such as that shown and described in the patent to Thomson No.1,121,953, dated December 22, 1914. e

What I claim is: v

1. In a telephone system, a subscribers line, a counting device for saidline, connecting circuits for establishingtalking connections with saidline, a source of current, a supply circuit common to the connectingcircuits for feeding current from said source to said connectingcircuits, means responsive to the'establishment of a talking connectionover one of the connecting circuits for connecting the supply circuit tosuch connecting circuit, meansrepeatedly reversing the direction of]current flow in the supply cir cuit, and means responsive to suchreversals during the conversational period for operati ing said countingdevice.

2. In a telephone system, a calling line and a called line, a meter forthe calling line, connecting circuits for establishing talkingconnections between said lines, a source ofcurrent, a supply circuitcommon to the connecting circuitsforfeeding current from said source tothe calling line, means rendered effective by the response of the calledsubseriber for connecting the supply circuit to the particularconnecting circuit used for the talking connection, means for repeatedlyreversing the direction of curerntfiow in the supply circuit, and meansresponsive to such reversals for opertaing said meter.

- 3. In a-telephone system, a subscribers line,

a meter for said line, connecting circuits for establishing talkingconnections with said line, a source of current, a supply circuit commonto said connecting circuits for feeding current from said source to saidconnecting circuits, relays, one for each connecting circuit, meansresponsive to the establishment of a talking connection over one of saidconnecting circuits for operating the individual relay to connect thesupply circuit to such connecting circuit, means for periodicallyreversing the direction of current flowing in the supply circuit, andmeans responsive to such reversals for'operating the subscribers meter.

4. In combination, a subscribers line having a meter at the sub-station,connecting circuits for establishing talking connections with said line,a source of current, a supply circuit common to said connecting circuitsfor feeding current from said source to said connecting circuits, saidsupply circuit being normally disconnected from said connectingcircuits, means responsive to the establishment of a talking connectionover one of the connecting circuits for connecting the supply circuitthereto, time controlled means for periodically reversing the directionof current flow in the supply circuit and in the subscribers line, andmeans responsive to such current reversals in the subscribers line foroperating said meter.

5. In combination, a subscribers line, a recording device for said line,a number of connecting circuits for establishing talking connectionswith said line, a source of current, a battery feed circuit forsupplying current to said connecting circuits, means effective inresponse to the establishment of a talking connection over one of saidconnecting circuits for connecting the battery feed circuit to saidconnecting circuit, means for repeatedly reversing the direction ofcurrent flow in the battery feed circuit to operate said recordingdevice, and means in the battery feed circuit for preventing suddenchanges of current.

6. In a telephone system, a subscribers line, a meter for said line,connecting circuits for establishing talking connections with said line,a source of current, a supply circuitcommon to the connecting circuitsfor feeding current from said source to said connecting circuits, meansfor repeatedly reversing the direction of current flow in the supplycircuit to operate said meter, and impedance elements in the supplycircuit for preventing sudden changes of current.

7. In combination, a subscribers line, a meter for said line, connectingcircuits for establishing conversational. connections with said line, asource of current, a supply circuit common to said connecting circuitsfor feeding current from said source to said connecting circuits, meansfor connecting said supply circuit to any one of said connectingcircuits,

means for periodically reversing the direction of current flowing in thesupply circuit to operate said meter, and inductance and capacityelements in said supply circuit for preventing sudden changes of currentdue to reversal of direction.

8. In a telephone system, a subscribers line, a meter at the substation,connecting circuits for establishing talking connections with said line,a source of current and a supply circuit common to said connectingcircuits, relays, one for each connecting circuit for connecting saidsupply circuit to said connecting circuit, and means for periodicallyreversing the direction of current flowing in the supply circuit tooperate said meter.

9. In combination, a subscribers line, a meter for said line, connectingcircuits for establishing talking connection with said line, repeatingcoils one for each of said connecting circuits, a source of current, asupply circuit common to said connecting circuits, relays, one for eachconnectingcircuit for connecting said supply circuit through the windings of the repeating coil to the corresponding connecting circuit,means responsive to the establishment of a talking connection over oneof said connecting circuits for operating the corresponding relay, andmeans for periodically reversing the direction of current flowing in thesupply circuit and subscribers line to operate said meter.

10. In a telephone system, a calling subscribers line and a measuringdevice therefor, a called subscribers line, means for establishing aconnection between said lines, a current controlling device forrepeatedly changing the current in the calling line to actuate saidmeasuring device, time delay means rendered operative by the response ofthe called party, and means controlled by said delay means for renderingeifective said current controlling device.

11. In a telephone system, a calling subscribers line and a metertherefor, a called subscribers line, means for establishing a connectionbetween said lines, a current reversing device for repeatedly reversingthe direction of current in the calling line to ac-- tuate said meter,and timing means rendered operative by the response of the called partyand serving after an interval to render said current reversing deviceeffective.

12. The combination in a telephone system of a calling line and a calledline, a meter at the calling substation, means for interconnecting saidlines for conversation, a device for periodically reversing thedirection of current in the calling line to operate said meter duringconversation, means controlled by the response of the called party forrendering said reversing device effective, and means for causing a delaybetween the response of the called party and the time when said deviceis rendered efiective.

13. The combination in a telephone system of a calling line and a calledline, a meter at the calling substantion, means for establishing aconnection between said lines, a current controlling device forperiodically changing the current in the calling line to actuate saidmeter, a supervisory relay operated when the called party answers, atiming device set in operation by said supervisory relay, and meanscontrolled by said timing device for rendering effective said currentcontrolling device.

14:. In. a telephone system, a calling line and a called line, means forinterconnecting said lines, a message meter for the calling line, acurrent reversing device for repeatedly reversing the direction ofcurrent in the callinp' line to operate said meter, a relay forconnecting said device to the calling line, a timing means controlledover the called line, and means controlled by said timing means after adefinite interval for operating said relay.

15. The combination in a telephone system of a calling line and a calledline, a me ter at the calling substation, means for establishing atalking connection between said lines, a device for repeatedly reversingthe direction oi current in the calling line to opcrate saidmeter'during conversation, means controlled by the response of thecalled party for rendering said device effective, and means forrendering said last means ineffective in order to distinguish between anoriginal call and a recall by the calling subscriber.

16. The combination in a telephone system of a calling line and a calledline, a meter at the calling substation, means for establishing atalkingconnection between said lines, a device for repeatedly reversingthe direction of current in the calling line to operate said meterduring conversation. means controlled by the response of the calledparty for rendering said device effective, an operators position, andmeans controlled by the operator in answering a recall to prevent saidlast means from rendering the reversing device effective.

17. In combination, a subscribers line having a bell and a meter at thesubstation, means for establishing a connection with said line, aringing device comprising direct current and alternating currentsources, means for connecting said device to the line to ring said bell,means for preventing the direct current from flowing over said linewithout preventing the flow of the alternating current,

and means for operating said meter.

18. In a telephone system, a telephone line having a bell and a meter,means for establishing a connection with said line, a ringing devicecomprising direct current and alternating current sources, means forapplying current from both sources to said line, means controlled oversaid line to disconnect the direct current source therefrom without disafor est-ablishin 1 line, a source o? connecting the alternating currentsource, and means for operating said meter.

Y 19. In a telephone system, a subscribers line, a meter for said line,connecting circuits 0 talking connections With said current, a supplycircuit common to the connecting circuits for feeding current from saidsource to said connecting circuits, means responsive to theestablishment of a talking connection over one of the connectingcircuits for connecting the supply circuit to such connecting circult,means repeatedly reversing the d rection of current flow in thesupplycircuit, means responsive to such reversals during theconversational penod for operating the subscribers meter, and means toprevent the connection of the supply circuit to a, connecting circuitwhile the current, is reversed.

20. In combination, a telephone line, connecting circuits forestablishing connections with said.line,a source of current, a supplycircuit for supplying current from said source to-said connectingcircuits, means for connecting said supply circuit to one ofsaidconnecting circuits, means for repeatedly reversiiig the direction ofcurrent flow in the supply'circuit, anda timing device for prevent--in'grthe connection-of the supply circuit-to a connecting circuit whilethe current is reversed.

.- In witness jwvhereof, I hereunto subscribe "my name this 13th day ofJanuary, 1928.

' LEWIS H. JOHNSON.

